In mineral exploration, drilling is the critical and expensive operation of obtaining rock specimens such as core samples from a geological body. Once obtained, the rock specimens are studied in numerous ways for indications that there may be valuable, retrievable mineral deposits in the geological body.
A large number of core samples are typically extracted from a particular geological body in order to provide useful indications of the mineral contents contained within the body. Typically, a given core sample extracted from a geological body is initially an elongate, generally-cylindrical rock specimen of a few centimeters in diameter and several centimeters long. Upon extraction, the core sample is uniquely identified and very often further “sampled” by splitting the generally-cylindrical core sample into, for example, a number of half- and/or quarter- and/or three-quarter cylinders. The individual samples of an initial core sample are then distributed to one or more laboratories for geochemical and/or geometallurgical analysis, as well as to one or more geologists for geological and/or geophysical study and analysis. For example, structurally relevant core samples and pieces thereof form the foundation of Structural Vectoring®—a process of understanding a mineral body using structural geological analysis, as described in“Structural Vectoring In Mineral Exploration: What It Is And How, When and Why We Should Use It” (Monteiro, http://vektore.com/2016/02/18/structural-vectoring-in-mineral-exploration-what-it-is-and-how-when-and-why-we-should-use-it/).
As a result of analyses of the individual samples, plotted maps/sections are created for a given core sample and/or a three-dimensional model is made of the core sample for visualization and statistical analysis. Geologists generate this information from several extracted core samples and use it to produce a mineral resource analysis for the geological body. Such an analysis may include the configuration or design of mineral bodies within the overall geological body being investigated, as well as the volume and grade distributions.
Because the physical core samples themselves embody a great deal of information, they serve as a significant resource to the mining operation, particularly for validation and auditing. Mining operations invest considerable resources to store, preserve and make core samples available during a given project and for future ventures. The extracted and analyzed core samples pieces that remain onsite, being central to the mineral resource analysis, are catalogued, physically stored in boxes, and stacked in core farms so that they may be physically accessed repeatedly for further analysis and/or site audits. As for further analysis, often geologists overlook important geological features during a first pass or even a main logging stage of a project or an audit.
Traditionally, if further work with the core samples were to be required, the geologists had to be physically present at the core farm to handle and study the samples in person. Many exploration sites are in remote locations, and it can be expensive and time consuming for geologists to always be present onsite.
In order to reduce some of the effort, time and expense of geologists having to be physically onsite to study core samples, some mining operations have been employing core sample scanners to digitally capture images of core samples. The digital images can then be electronically shared with the geologists in different locations. One example of a commercially-available core sample scanner is the CoreScan 3 offered by the DMT Group. The CoreScan 3, described at the website http://www.dmt-group.com/en/products/geo-measuring-systems/dmt-corescan.html, is configured as a tabletop kiosk unit with an open lower table portion and an upper imager portion for imaging objects placed onto the open table portion. The table portion can receive core samples for flat (two-dimensional) scanning of core samples. For three-dimensional scanning, the table portion also includes mechanical rollers that can both support and roll a heavy cylindrical core sample about a horizontal axis while the imager portion captures image data of all sides of the core sample from above. A downstream processing unit is configured with appropriate software for processing the captured image data to create a three-dimensional model of the cylindrical core sample for study and analysis. According to the published specifications of the CoreScan 3, the unit has a length of 1.36 meters, a height of 1.28 meters, and a weight of 128 kilograms.
While the CoreScan 3 is a useful tool, its size and weight limit where and when it can be used. As explained in the publication entitled “A Portable Core Imaging Scanner” (Kofman, Duerksen and Schmitt, University of Alberta, Edmonton, Alberta, Canada—2012), one reason that core imaging has not been more accepted is that the available equipment is relatively bulky such that its use is not usually practical. Research sites are often remote and rugged, potentially limiting the amount and types of equipment that can be brought onsite by investigators for data acquisition and analysis. The Kofman et al. paper proposes a similar, roller-based core sample scanner for receiving horizontally-oriented cylindrical core samples, and offers that constructing such a device using aluminum for some components would provide a superior cost and strength to weight ratio, thereby perhaps making it less difficult to get into the more remote and rugged sites.
The CoreScan 3 and the device proposed by the Kofman et al. paper include several moving parts in order to enable them to physically support and roll core samples for imaging. With high-volume core sample scanning operations, rollers, bearings, motors and other such moving parts exposed to dust, rock fragments and frequent use are of course subject to failure. If a scanner having such parts is required to be moved to a different location, the moving parts are also at risk of being knocked out of alignment. As such, maintenance costs of such physically-complex units can be significant. Furthermore, components such as motors, bearings and rollers suited to physically supporting oftentimes heavy core samples will typically be constructed with steel. They will therefore contribute greatly to overall weight, despite the weight savings from using lighter materials such as aluminum for other components.
In addition, core sample scanners that employ horizontal rollers to support and roll cylindrical core samples during imaging do not easily accommodate non-cylindrical core samples such as the half-cylinder, three-quarter cylinder, or quarter-cylinder samples into which an originally-cylindrical core sample can be divided. As would be understood, rolling a non-cylindrical core sample would result, essentially, in uncontrolled tumbling of the core sample during attempted rotation, making it very difficult to capture images suitable for forming a useful three-dimensional model. Because of this, if a three-dimensional scan of a non-cylindrical core sample is required, the technician using the core sample scanner must get quite involved by manually manipulating the core sample instead of allowing it to tumble freely. This manual manipulation tends to significantly lengthen the scanning time, reducing the efficiency of the overall operation. As such, improvements are desirable.